Blender Git Loki

Cycles X: Remove zero_to_device from RenderBuffers::reset()

In all the current usages of RenderBuffers::reset the zero was
actually redundant.

This change makes it easier to allocate temporary render buffer
and copy data to it as a part of a specific stream without zero
(which happens in the default stream) conflicting.

Differential Revision: https://developer.blender.org/D11740